What drove me away from WoW ?
In one word, casualization.
Less involvement required, destruction of progression, automated grouping and teleportation, leveling made ultra-fast and just as ultra-boring. Game becoming non-rewarding and instant gratification and the like.
Too much convenience and the loss of fluff/flavour. Too many changes about the core game drawing it away from what was good in it.

Everything is accessible through queues, with little-to-no need to venture outside of cities
Dailies shouldn't be a requirement for progression
Gear is too easy to obtain / Epics don't feel epic
Leveling up is a race rather than an adventure

Simply put: While the game has had a lot of quality of life improvements over the years, it has strayed too far from its roots that made it interesting and fun

Everything is accessible through queues, with little-to-no need to venture outside of cities
Dailies shouldn't be a requirement for progression
Gear is too easy to obtain / Epics don't feel epic
Leveling up is a race rather than an adventure

Basically none of those for me. Like, mirrored opinions on whether or not those are bad/good things.

What drove me away just before 5.2 was the side-effects being on a PVP server with a PVE-oriented guild of friends that I was 10m raiding with. Namely, endlessly getting ganked just trying to level alts or do my dailies and then the pressure to play a certain class and spec that I didn't want to thus making raiding not just a chore but like a bad job I didn't want or need to be at. Came back in 5.3, entire guild moved to a PVE server and most of the guild is happy with the concept of flex raiding to bring along less progression-driven members (like myself) in order to help gear and train as many people as possible on the SoO mechanics.

If I fall out again and it's not a money issue, it'll likely be the same thing. I'll end up taking the game too seriously, push myself into a position I'm not comfortable conforming to and ultimately drop the game for a patch or two, again. (As a side note, unlike quite a few people here, when I stopped playing the game, I also stopped posting to WoW forums. I understood that if I didn't play a patch live, I didn't know how good or bad the content was.)

I quit in Cata, and the direct cause was the guild breaking down (going 10 man, which inevitably lead to stopping raiding the next tier) and me not wanting to raid 10 mans. The guild was the only thing keeping me in the game at that point. It's just not possible to run a solid 25 man guild anywhere outside the handful of high population servers (and transferring there would've cost me $100+). Then there's always the players who are nagging "lets just scale down to 10 man with our 10 best players and clear everything faster and easier", which gets tiring after a while when you'd really want to be focusing on progress and improvement instead of the same old argument for cheesing it in 10 man.

I could never get into the whole 10/25/easy/hard nonsense with gear resets in every patch. I just wanted the linear progression feel of TBC where you work on a boss for a few weeks, killing of which opens up a brand new boss and part of the instance. The new model just felt like a boring grind that wasn't even advancing your character in real terms because you'd just get new gear for free in the next patch regardless of what you did in the previous patch. It also meant that players no longer cared about their guilds and would come and go, knowing that they could always get back to the latest content at any point.

There's also a host of other things. Like the content quality plummeting (raid instances became just excuses to house loot pinatas instead of epic ,well designed raids like Kara, BT, Ulduar, etc.). Blizzard scamming me (promising, in writing, that Cata would contain more raid content than WotLK, and then delivering barely half that). Everything getting dumbed down and the game just feeling like a cash cow instead of something the developers had read passion for.

basically lack of immersion and the fact that Blizzard is handing us everything on a silver platter

I used to be casual in vanilla and I loved it; epics where still epic and any epic item I got as casual felt really like an accomplishment.
Now it's just queuing for dungeons or raids and brainlessly spam buttons and get free loot.

The game lost its magic because of Blizzards policy of making all content accessible to everyone. It just makes your Illidan, Lich King, Deathwing kinds of villains less epic, and it reduces your interest in the community because a) you no longer care about the top-guilds like I used to care about Nihilium back in the old days, b) everyone is running around in the latest fancy tier-set looking the same, so you no longer identify the top players form the best guilds on the realm flexing in Orgrimmar and dreaming that one day you could slay that dragon and obtain that epic - and the whole immaterial thing of having something to aspire to, to dream of, a goal far of in the distance - adds more to the entire experience of World of Warcraft which makes you stick around than having all game content accessible. I feel they made a mistake in going all-out on accessibility, I believe they could've peaked during Wrath with the same number without making all raid content accessible. Instead of just adding layers of difficulty on the same raid they could've had 2 raids for each tier, one that is flex and is quite easy to run where you defeat the say.. "Lieutenants of the Lich King" in a wing or two of Icecrown Citadel. Running that makes you attuned to enter the main entrance, which is a damn hard raid where a super epic Lich King is the end boss.

"Driven off by the epic shitbag disaster that was Cataclysm? Don't worry, we've created some fucking silly-ass panda shit to lure you back! NO THIS ISN'T AN EARLY APRIL FOOLS, YES WE TURNED THAT ONE PANDA JOKE CHARACTER IN WC3 INTO AN ENTIRE EXPANSION! QUIT LAUGHING AT US!"

That's like half their subscription decline right there.

This is what drove me from WoW, this and WoW no longer having mountains to climb so to speak.

Outside of PvP, where difficulty is determined by your opponents WoW's accessibility was too high, and it's the reason people idealize Burning Crusade/Classic.

1. I stopped at the end of WOTLK. I had killed the Lich King and every other boss apart from LK Heroic 25. But I could not imagine it being a better feeling then the major letdown I had when I killed LK normal. My major quest to start WoW to begin with was finished. I killed Arthas, be it on normal. Killed the rest of ICC 25 heroic tho. Just not LK and I couldn't care.

2. In Cata I came back and went full throttle. Tho then we had some internal struggles in the guild and we needed a few more recruits which we were unable to find. That coincided with me getting a girlfriend and thus I quit. Guild soon after fell apart and well there was not much to go back to.

3. After I deal with 5.4, I will quit again probably until the next expansion. Since Pandaria I am very very casual as opposed to being pretty damn hardcore before (Cata and before). And I will quit again because MoP is so accessible and everything is handed to you on a platter vs other expansions I have played. I just can't stand that. When things are very very new I can still get enjoyment out of the expansion/patch. But after that I will quit. So you'll likely see me sub/unsub/sub/unsub or totally quit.

2 things. First I'm hating the direction of the story telling. Not the Pandarin part but the part where Blizz only capable of pandering to 1 faction. The second thing is time. I have a kid now and he takes most of my time.

1. the Talent changes. The old one I enjoyed. and you could try different things, and you felt great when you got your first point for the first time at level 2.

2. was changing how players had to play there champ. When you first play wow back in the day it took time to get to know your champ, and what your limits were. After getting to know your champ, and then you get slapped in the face with the new system, and your like wow. I can't bubble heart, I can't control my pet. I can't mess around with mixing ability's up.

Now how old, and far did I get? Well when I quite wow. I had most of the achievements from naxxramus, outland, and many others. I was still working on the new legendary daggers when I stopped playing. Once I saw so many changes coming. I just sad to my self there is no point on even playing any more if they are going to change every thing.

People can say what they want, but those are what made me just stop playing.